ContextWindow: Use Task.Run to load data outside main thread

Elwig/Windows/MemberAdminWindow.xaml

@@ -5,8 +5,7 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:local="clr-namespace:Elwig.Windows"
         xmlns:vm="clr-namespace:Elwig.ViewModels"
-        Title="Mitglieder - Elwig" Height="700" Width="1250" MinHeight="650" MinWidth="1150"
-        Loaded="Window_Loaded">
+        Title="Mitglieder - Elwig" Height="700" Width="1250" MinHeight="650" MinWidth="1150">
     <Window.DataContext>
         <vm:MemberAdminViewModel/>
     </Window.DataContext>